There is a conventional apparatus for conveying powder comprising:
a pressure tank comprising:                a rotary valve, which ejects a predetermined amount of powder from the pressure tank, driven by a motor and disposed at the bottom of the pressure tank,        a receiving port having a damper and disposed at the top of the pressure tank,        a first pressure gauge disposed at the pressure tank,        a load cell to weigh the pressure tank,        wherein the pressure tank is supported by means of the load cell,        
a supply tank disposed above the pressure tank, comprising:                a feeding port having a damper and disposed at the top of the supply tank,        a discharging port disposed at the bottom of the supply tank,        a second pressure gauge disposed at the supply tank,        
wherein the load cell and the dampers are electrically connected to a control unit for computing measurements and controlling devices,
wherein the receiving port of the pressure tank communicates with the discharging port of the supply tank by means of a damper and a pipe that can be extended and contracted,
wherein the upper and inner portions of the pressure tank communicate with those of the supply tank by means of a pipe and two opening and closing valves,
wherein a discharging pipe communicates with the point between the two opening and closing valves disposed in the piping, and
wherein the first pressure gauge and the second pressure gauge are electrically connected to a control unit for comparing and computing measurements.
Patent Document 1: Japanese Patent Laid-Open Publication No. H10-35886